Chlorzoxazone
Also sold as: Lorzone
Related Medications
These drugs share a pharmacologic classification but are NOT interchangeable. Listing here does not imply clinical equivalence. A physician must evaluate each drug individually for the patient's specific condition.
Classification: Centrally-mediated Muscle Relaxation (source: RxClass/NLM)
Insurance Coverage User-Reported
No community coverage data yet for chlorzoxazone.
Coverage data submission coming soon.
Drug Information
Indications & Uses
INDICATIONS Chlorzoxazone is indicated as an adjunct to rest, physical therapy, and other measures for the relief of discomfort associated with acute, painful musculoskeletal conditions. The mode of action of this drug has not been clearly identified, but may be related to its sedative properties. Chlorzoxazone does not directly relax tense skeletal muscles in man.
Dosage & Administration
DOSAGE AND ADMINISTRATION Usual Adult Dosage One tablet three or four times daily. If adequate response is not obtained with this dose, it may be increased to one and one-half tablets (750 mg) three or four times daily. As improvement occurs dosage can usually be reduced.
Warnings & Precautions
WARNINGS Serious (including fatal) hepatocellular toxicity has been reported rarely in patients receiving chlorzoxazone. The mechanism is unknown but appears to be idiosyncratic and unpredictable. Factors predisposing patients to this rare event are not known. Patients should be instructed to report early signs and/or symptoms of hepatotoxicity such as fever, rash, anorexia, nausea, vomiting, fatigue, right upper quadrant pain, dark urine, or jaundice. Chlorzoxazone should be discontinued immediately and a physician consulted if any of these signs or symptoms develop. Chlorzoxazone use should also be discontinued if a patient develops abnormal liver enzymes (e.g., AST, ALT, alkaline phosphatase and bilirubin.) The concomitant use of alcohol or other central nervous system depressants may have an additive effect. Usage in Pregnancy The safe use of chlorzoxazone has not been established with respect to the possible adverse effects upon fetal development. Therefore, it should be used in women of childbearing potential only when, in the judgment of the physician, the potential benefits outweigh the possible risks.
Side Effects (Adverse Reactions)
ADVERSE REACTIONS Chlorzoxazone containing products are usually well tolerated. It is possible in rare instances that chlorzoxazone may have been associated with gastrointestinal bleeding. Drowsiness, dizziness, lightheadedness, malaise, or over-stimulation may be noted by an occasional patient. Rarely, allergic type skin rashes, petechiae, or ecchymoses may develop during treatment. Angioneurotic edema or anaphylactic reactions are extremely rare. There is no evidence that the drug will cause renal damage. Rarely, a patient may note discoloration of the urine resulting from a phenolic metabolite of chlorzoxazone. This finding is of no known clinical significance. To report SUSPECTED ADVERSE EVENTS, contact Aurobindo Pharma USA, Inc. at 1-866-850-2876 or FDA at 1-800- FDA-1088 or http://www.fda.gov/ for voluntary reporting of adverse reactions.
Contraindications
CONTRAINDICATIONS Chlorzoxazone is contraindicated in patients with known intolerance to the drug.
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Medical Disclaimer: Information on this page is sourced from FDA-approved labeling data and is for educational reference only. It does not constitute medical advice. This information does not establish a provider-patient relationship. Always verify with current prescribing information and consult a licensed healthcare professional before any clinical decision. Read full disclaimer.
Data sourced from RxNorm (NLM/NIH), FDA Orange Book, OpenFDA, DailyMed. Last updated: 2026-03-02.